Am Fungi - Chemotaxis The Amorpha Symbiont Caused Rhizobia And Nod Factor-induced,

Arbuscular mycorrhizal(AM) fungi could form symbiosis relationship with more than 80 percent terrestrial plant and plays an important role. AM fungi could also form tripartite symbiosis with rhizobia and legume plant. The three benefit one another and AM fungi could enhance the nitrogen fixing ability of the symbiosis significantly.In this paper, through the study of inoculation (AM) treatment of Amorpha fruticosa, using the root organism chemotaxis method to test the chemotaxis between rhizobia and AM fungi under different infection rate; to study the effects of AM fungi under different infection rate on the secreted of Nod factor using HPLC and bioactivity method; through the study of addition nod factor(Nod+), addition of AM fungi and nod factor(AM+Nod+)and the control(CK), the effect of Nod factor to the stem length, fresh weight and root length of Amorpha fruticosa is also studied.The results suggested that it is obviously the signal molecules of AM fungi, rhizobia and Amorpha fruticosa have identification procedure, under 25% infection rate antagonistic turns to synergistic while under 50% reaches maximum; it is also showed that the root exudates of AM treatment could affect the secretion to increase the amount of nod factor and quality of the nod factor detected. But the increase is negative with the chemotaxis; it could also be known that nod factor could nodulate independently, and AM fungi could increase the number of nodules; the greater quality nod factor is, the greater positive effect on the infection of AM fungi; and the biomass of Amorpha fruticosa such as the fresh weight, stem length and root length has also been improved, greater effect is shown on the co-addition(AM+Nod+).All results suggested that AM fungi could increase the concentration of nod factor to improve the nitrogen fixing capacity of Rhizobia while nod factor react up on AM fungi to accelerate the infection rate, and thus AM fungi and Rhizobia could benefit each other in the tripartite symbiosis.